The biochemical genetics of post-mitotic cellular longevity are being investigated employing the fungus Neurospora crassa as a model. The importance of specific single gene mutations in the reduction or enhancement of cellular longevity is being delineated. The function of specific longevity genes is being examined in terms of the free radical theory of aging and "anti-radical" enzymes such as superoxide dismutase, catalase and glutathione peroxidase.